This invention relates to a safety clip for identifying and securing a circuit breaker in an open position with the safety clip""s size and shape selected such that the safety clip can be easily installed and removed without contacting and damaging the electrical panel housing the circuit breaker.
The function of a circuit breaker is to serve as a safety device that either completes an electrical circuit or halts the flow of current through the electrical circuit when open. Moreover, circuit breakers are generally designed to automatically switch from a closed state to an open state, i.e., trip, upon sensing excessive current flowing through the electrical circuit. In most residential and industrial settings, rows of circuit breakers and circuit breaker labels that identify the respective circuit breakers are arranged in electrical panels. The circuit breaker rows may be recessed. In the aircraft industry, for instance, electrical panels may contain rows of lighted plates carrying identification decals positioned alongside recessed rows of circuit breakers to facilitate identification of the circuit breakers, particularly in low light conditions.
Before performing maintenance operations on any electrical system, one typically removes power to the electrical system by opening the circuit breaker associated with the particular system. In the aircraft industry, maintenance personnel must open the circuit breakers for a number of subsystems. For example, the circuit breakers for the primary and secondary flaps, engine ignition, window heat, weather radar, and avionics systems are opened prior to initiating most maintenance operations. Opening the circuit breaker and making sure the circuit breaker remains open until the maintenance is finished is imperative for the safety of the people performing the maintenance on the associated electrical system. In addition, the premature closure of a circuit breaker during maintenance of the associated electrical system may damage or destroy the electrical system itself. Conversely, failing to properly close a circuit breaker following completion of the maintenance operations and prior to flight may create difficulties. An open circuit breaker may cause the aircraft to fail its preflight check or cause problems during flight because the electrical system associated with the circuit breaker is inoperable.
Circuit breaker safety clips are commonly utilized to identify and secure the circuit breakers in the open position and to warn others not to close the circuit breaker so as to apply power to that electrical circuit. The safety clips are attached to at least part of the open circuit breaker so that one cannot close the circuit breaker without removing the safety clip. In this regard, a circuit breaker typically has a handle that is toggled between the opened and closed positions, such as being pushed inward and pulled outward, respectively. The handle, in turn, generally has a stem and a head mounted on the distal end of the stem. As such, circuit breaker safety clips are generally designed to attach to the stem of the circuit breaker handle so as to prevent the handle from moving to the closed position.
The safety clips may also carry a warning tag. For example, in the aircraft industry, a warning tag with the words xe2x80x9cREMOVE BEFORE FLIGHTxe2x80x9d or the like is affixed to the safety clip. The warning tag reminds maintenance personnel to remove the safety clip and close the circuit breaker following completion of the maintenance so that the respective electrical system is enabled during the preflight check procedure.
For each of the foregoing reasons, the safety of the people performing work on electrical systems and the condition of the electrical systems depend upon the proper installation of circuit breaker safety clips. Likewise, the proper operation of the aircraft following the maintenance depends upon the removal of the safety clip and the closure of the circuit breaker.
At least two types of circuit breaker safety clips are presently available, however, neither is suitable for use in all electrical panels, particularly not in electrical panels with recessed rows of circuit breakers. One type of conventional safety clip has an elongated, rectangular shape with two arms at one end to engage the circuit breaker head and a slit at the opposed end for attaching a warning tag, typically by means of rivets or the like. Unfortunately, the rectangularly shaped safety clip is too large to install and remove without difficulty and without damaging the electrical panel. To use these safety clips in electrical panels with recessed rows of circuit breakers, one must physically force the clip into engagement with a circuit breaker within the electrical panel. Forcing the safety clip into engagement with a circuit breaker within the electrical panel causes scratches and gouges to the electrical panel face, specifically the identification decals located between the rows of circuit breakers. If this damage goes without repair, it may be difficult to identify the circuit breakers because the information imprinted upon the identification decal is scratched off. Alternatively, the identification decals and/or the plate that carries the identification decal may be repaired or replaced, albeit at some cost of time and money. In addition, the size of the warning tag attached to this safety clip is generally quite large. When maintenance personnel use these safety clips, the warning tag may obstruct the view of the rest of the electrical panel and make it difficult to determine the status of the other circuit breakers.
The other type of conventional circuit breaker safety clip has a pair of arms defining a xe2x80x9cUxe2x80x9d -shape for engaging the circuit breaker head. This conventional circuit breaker safety clip also has a keystone-shaped feature on the side of the clip that is opposite the opening in the clip, which may be grasped to assist in removing the safety clip. This safety clip is not suitable for use in all areas of an electrical panel because the keystone shaped feature may contact the plates located between the rows of circuit breakers and prevent the safety clip from properly engaging the circuit breaker. Furthermore, even in the areas of the electrical panel where this safety clip properly engages at least part of the circuit breaker, it is difficult to remove once it is installed because the safety clip design is too small for some personnel to grasp. A warning tag is also commonly attached to this conventional safety clip with a simple plastic cord. Nevertheless, the lack of a durable attachment for the warning tag to the safety clip increases the possibility that the warning tag will become detached from the safety clip. Without the warning tag, the safety clip may be overlooked during, for instance, a preflight inspection, which would increase the time of the preflight inspection and decrease the efficiency of the ground maintenance operations.
For the reasons described above, some maintenance personnel resist using conventional safety clips. The conventional safety clips may cause damage to the electrical panel, carry inadequate warning tags, and/or be unnecessarily difficult to install or remove. Thus, there is a need for a circuit breaker safety clip designed to properly engage circuit breakers in all the common electrical panels without damaging the panel face, light plates or identification decals. There also exists a need for a circuit breaker safety clip that has a properly sized and durably attached warning tag.
In accordance with this invention, a safety clip and an associated method are provided to identify and secure circuit breakers in an open position. The size and shape of the safety clip are selected such that the safety clip does not damage electrical panels and provides ease of installation and removal. Additionally, the safety clip may include a warning tag that is durably attached and is appropriately sized to be noticeable without blocking the view of other circuit breakers. Still further, the safety clip may serve to protect at least part of the circuit breaker, typically the circuit breaker head, from direct impact.
According to one embodiment, the cross-section of the safety clip is C-shaped with a first portion defining an opening to receive and engage at least part of the circuit breaker, such as the circuit breaker stem. The safety clip also includes a second portion that is spaced from the first portion and wraps about at least part of the circuit breaker, such as the head of the circuit breaker, so as to protect the circuit breaker from direct impact. The second portion also defines a recess for receiving a warning tag. The safety clip is preferably designed such that this recess opens in the same direction as the opening of the first portion, thereby permitting the safety clip to have the C-shape that serves to protect the circuit breaker and reduce the overall size of the safety clip. The safety clip may also include a third portion that connects the first and second portions and, in some embodiments, defines an aperture for receiving another tag, if necessary.
The first portion of the safety clip defines an opening to receive and engage at least part of the circuit breaker. In one advantageous embodiment, the base of the first portion, i.e., the side of the first portion facing away from the second portion, is shaped to ease the installation and removal of the safety clip and provide clearance between the safety clip and the electrical panel face. This embodiment thereby prevents the damage to the electrical panel that may be caused by conventional safety clips. In this regard, a portion of the base facing the first direction may be angled and, in one embodiment, the opposed portion of the base facing away from the first direction may also be angled.
The recess defined by the second portion of the safety clip is commonly a slit for receiving a portion of a warning tag, which is attached thereto. The side of the second portion that faces the first portion may also be angled to the degree necessary to allow for ease of installation and removal of the safety clip. The shape of this embodiment is such that the safety clip can be installed or removed without the second portion contacting at least part of the circuit breaker.
The safety clip of the present invention can therefore securely engage a circuit breaker in an electrical panel such that the circuit breaker must remain in an open position while the safety clip is attached thereto. As a result of its design, the safety clip will not contact other portions of the electrical panel, such as the identification decals and associated light plates, even as the safety clip is rotated relative to the handle of the circuit breaker, thereby minimizing the possibility of damage to the electrical panel.
The safety clip design also allows for the safety clip to be easily installed and removed. Further, the safety clip permits attaching a warning tag in a durable fashion. The safety clip also permits a warning tag that is sized sufficiently to warn others of the safety clip""s presence without unnecessarily covering other portions of the electrical panel. Moreover, the wrap-around safety clip design of one advantageous embodiment not only provides protection by identifying and securing an open circuit breaker, but it also protects at least part of the circuit breaker, typically the head of the circuit breaker, from direct impact.